Optimization of DATA Transmission for
Transport Sector
User case, TMB
David Lumbreras
Project Area Manager
In this presentation:
• User requirements
• High efficiency in AVL Systems
– Comparing methods
• An example: TMB case
Fleet Manager Requirements:
 Traffic Bus Regulation.
 Frequency Improvement.
 Customer Service.
 Investment Optimization.
 Passengers Safety
How to do it?
 Voice Communications with the Control Centre.
 Half-duplex and duplex voice calls.
 Status and short data transmission.
 Vehicle sensors transmission.
 MMI integrated on driver’s dashboard.
 Interaction with passenger information system.
 GPS-based location system.
How often is needed?
 Data User Requirements:
 Continuous Actualization of Data in Control
Centre.
 Normally 20/ 30 second each Terminal.
User Requirements
Bus on-board equipment
Example: CONFIGURATION STRUCTURE
Control unit
Bus
driver’s
MMI
TETRA MS
PEI
Bus driver’s
audio system
- PTT
- Emergency button
- Call request
Ambience
listening
microphone
Handset
Telemetry
sensors
Hands-free
audio kit
Audio
interface
Passenger
information
system
control
Billing
system
data
DISPLAY
Other
peripherals
engine,
speed,
doors...
Bus on-board equipment
Example: INSTALLATION DETAILS
Control unit
Bus system
interface
TETRA
radio
Passenger
information
system
Micro speaker &
hands-free mic
Driver’s MMI console
Looking for the most efficient way for
DATA TRANSMISSION with TETRA
technology
High efficiency in AVL, Comparing Methods
• In this type of scenario it is necessary to analyse carefully the
geographic positioning as the stronger requirement.
•
Short Data Messages (SDS) comparing to Packet Data Protocol (PDP), the
conclusions are:
MCCH Occupation
100%
Nº slots
4
3
75%
2
50% 49%
1 (MCCH)
Polling SDS
Random SDS
Polling PD
Random PD
25%
Type of service
Scenario example
500 buses.
30 seconds of latency for all buses.
20 bytes of information size.
3 coverage sites (SBS).
With these conclusions, we are going to work with SDS polling to obtain
the geographic positioning.
High efficiency in AVL, Comparing Methods
• With the standard SDS procedure the requirement for the
network is still strong.
• So now, it is necessary to think beyond the TETRA technology.
• New option improving the efficiency.
• Packets used in MCCH to transmit 20 bytes of data.
Mobile in MCCH
1/2 slot downlink
1 slot uplink
1/2 slot downlink
SwMi
D_STATUS_REQ
ACK + SDS_DATA
ACK
System considerations.
Terminal considerations.
Status REQUEST+ slot granting (1).
Ack to Status + SDS data (160 bits)
SwMi acknowledge
High efficiency in AVL, Comparing Methods
• New optimised polling SDS is the best solution to this type of
application.
MCCH Occupation
Nº slots
4
100%
3
75%
2
50%
1 (MCCH)
Scenario example
49%
25%
Optimised
Polling SDS
Polling SDS
Random SDS
Polling PD
Random PD
Type of service
500 buses.
30 seconds of latency for all buses.
20 bytes of information size.
3 coverage sites (SBS).
TMB User case
8 SBS´s
1300 buses
High efficiency in AVL, Comparing Methods
• With the best service selected…
Now it is necessary to think how we are going to synchronize the different
CCHs.
Real scenario example
1300 buses.
20 seconds of latency for all buses.
20 bytes of information size.
8 coverage sites (SBS).
Here using 1MCCH and 3 SCCH per SBS:
• 15% of the control channel is used for geographic positioning.
To obtain this percentage it is necessary to synchronise all CCHs
TMB user case, High efficiency in AVL
Synchronising the polling means...
...obtaining
following figures:
8 SBS x 4 CCHs = 24 CCHs to request the bus position
1300 buses / ( 20 seconds x 24 CCHs ) = 3 buses per second per
CCH
Doing this polling is possible to obtain success with the application.
TMB user case, High efficiency in AVL
Synchronising the polling means...
The problem is:
External Application has not the capability to know where is located
every bus in every second.
So for this reason Infrastructure manufacturers have to give the
synchronism solution.
In that case the SwMi has to give to the applications provider several
commands to introduce the buses to be polling, then…
..... polling answer will come from the SwMi
Automatically.
TMB user case, High efficiency in AVL
Commands used by the application provider:
NEBULA
OUTPUT
COMMANDS
User Application
List of commands needed to
manage this application:
AVL-ADD-ISSI
AVL-DEL-ISSI
AVL-START-POLLING
AVL-STOP-POLLING
AVL-GET-POSITION
TMB user case, High efficiency in AVL
How the SwMi uses the ISSI list to poll at same time every CCH?
Real time operative system.
SwMi knows where all buses are placed so it can request them as same
time with an internal table.
This three ISSI lines will be
sent to poll the buses in one second
In 20 seconds all ISSIs on the
table have to be sent to the
base stations to poll the
complete buses fleet
SBS1
MCCH
70030
98439
34897
.
.
.
43677
467
33878
SBS1
SCCH1
89903
33432
34676
.
.
.
34768
34553
78898
34786
87555
67657
SBS1
SCCH2
34990
88998
34657
.
.
.
34566
33763
3433
SBS1
SCCH3
32122
83439
34686
.
.
.
34777
33
6676
67763
SBS2
MCCH
08578
34343
34577
.
.
.
76667
…..
…..
…..
…..
.
.
.
…..
…..
…..
…..
…..
…..
…..
SBS8
MCCH
32890
34788
43789
.
.
.
36776
SBS8
SCCH1
38767
43433
43763
.
.
.
47767
SBS8
SCCH2
9009
34988
34876
.
.
.
3476
SBS8
SCCH3
3487
4938
34767
.
.
.
33344
46673
46766
66667
53466
53443
34674
TMB user case, High efficiency in AVL
 Conclusions:
This solution can save around 60% of the channels in
the network, with respect to the other alternatives
Only synchronized polling generated by the SwMi can
manage with success this amount of data traffic
Thinking beyond the TETRA technology manufacturers
can give to the customers the final solution
Optimization of DATA Transmission for
Transport Sector
User case, TMB
Thank you for your attention
David Lumbreras
Project Area Manager